The overall objective of this research is to understand the biochemical mechanism of DNA replication. To this end, we are studying, in purified systems, the properties of DNA polymerases II and III and their interaction with non-polymerase facters known to be involved in DNA replication. We are also examining, in crude cell-free systems, the process of initiation of DNA synthesis on single- and double-stranded DNA templates. Studies will begin on the biochemistry of conversion of RNA to DNA in RNA tumor virus-infected cells.